1. Field of the Invention
The present invention generally relates to an optical printing apparatus for exposing light onto a photosensitive recording medium to form a gradation image. More specifically, the present invention is directed to such an optical printing apparatus. That is, while one column, or plurality of columns constituted by self-light emitting elements (e.g., LEDs and ELs), or light transmission control elements (e.g., liquid crystal shutter elements) or reflective elements (e.g., micro mirror elements) are arranged as a print head, the respective elements are independently controlled in response to image data so as to print out a gradation image in the optical printing apparatus.
2. Description of the Related Art
Various sorts of optical printing apparatuses have been developed as apparatuses employing instant films and simultaneous color paper, and are commercially available in the markets. In these optical printing apparatuses, light is exposed onto photosensitive recording media so as to form gradation images.
A conventional optical printing apparatus will now be explained with reference to a drawing. FIG. 22 is a perspective view for schematically indicating a structure of a print head used in one conventional optical printing apparatus as disclosed in, for instance, Japanese Patent Application Laid-open No. 7-256928.
In FIG. 22, white light emitted from a light source 5 is separated into red-colored light, green-colored light, and blue-colored light by way of a color liquid crystal (LCD) shutter 100. The R, G, B-colored light is continuously irradiated onto an edge surface of an acrylic rod 6 in a time shift manner. In this print head, the acrylic rod 6 is covered with a reflection foil on which aluminum and the like are vapor-deposited except for a light emitting plane thereof. Thus, this acrylic rod 6 owns such a function capable of effectively converting light entered from a rod edge surface into line-shaped light. As a result, the red line-shaped light, the green line-shaped light, and the blue line-shaped light are continuously irradiated onto a black/white shutter array 7 in a time shift manner.
In this case, 3 columns of pixel arrays corresponding to the red light, the green light, and the blue light are provided inside the black/white shutter array 7. These pixel arrays are driven in such a manner that only designated color light can pass therethrough. For example, when the red line-shaped light is irradiated, this red line-shaped light can pass through only one pixel array corresponding to the color light, whereas the other two pixel arrays are kept under shield condition. Then, the red line-shaped light, the green-shaped light, and the blue line-shaped light, which are modulated by the black/white shutter 7 are focused on a photosensitive paper such as the spectra instant film manufactured by Polaroid Inc., by using a SELFOC lens array 9 (namely, tradename of converging lens array). At this time, since the photosensitive paper is relatively transported with respect to the black/white LCD shutter array 7, the red line-shaped light, the green line-shaped light, and the blue line-shaped light are sequentially exposed onto the same place on the photosensitive paper. As a result, a two-dimensional print image can be obtained.
As previously described, since only three sorts of spectral image data (namely, red colordata, green color data, and blue color data) are exposed in the conventional optical printing apparatus, the following problem occurs. That is, the conventional optical printing apparatus can hardly print out the images having high image qualities, and especially form realistic images having material feelings.
Also, in the case that the light source or the self-light emitting elements with the narrow light band is employed in such a conventional optical printing apparatus, since the exposure wavelength range is narrow, there is another problem. That is, it is practically difficult to form the realistic images having material feelings, and also to perform the high image quality recording operation.
The present invention has been made to solve the above-explained problems of the conventional optical printing apparatus, and therefore, has an object to provide such an optical printing apparatus capable of forming an image by using more than 4 sorts of spectral image data. Also, another object of the present invention is to provide such an optical printing apparatus capable of realizing a high image quality recording operation by exposing color light onto a printing material by employing a plurality of light beams having different peak wavelengths within the same color system even when three sorts of spectral image data are used in the exposure operation. In particular, realistic images having material feelings can be formed by this optical printing apparatus.
To achieve the above-described objects, an optical printing apparatus, according to a first aspect of the present invention, is featured by such an optical printing apparatus for selectively exposing light with respect to a photosensitive recording medium to thereby form a gradation image thereon, comprising: image data input means for entering more than 4 colors of spectral image data; storage means for storing thereinto the entered spectral image data; an optical print head for outputting more than 4 sorts of light having different wavelengths from each other; and head driving means for converting the stored spectral image data into predetermined exposure time periods to drive the optical print head.
Also, an optical printing apparatus, according to a second aspect of the present invention, is featured by that the optical print head contains more than 4 sorts of light sources having different peak wavelengths from each other.
Also, an optical printing apparatus, according to a third aspect of the present invention, is featured by that the optical print head includes a white-light light source, and a color filter for penetrating therethrough more than 4-colors light emitted from the white-light light source.
Also, an optical printing apparatus, according to a fourth aspect of the present invention, is featured by that the optical print head includes a white-light light source, and an optical element for spectral-dividing the white light emitted from the white-light light source into more than 4-colors light.
Also, an optical printing apparatus, according to a fifth aspect of the present invention, is featured by that the optical print head includes self-light emitting elements arranged in an array shape in correspondence with the spectral image data.
Also, an optical printing apparatus, according to a sixth aspect of the present invention, is featured by that light emitted from an exposure light source is arranged in a stagger shape.
Furthermore, to achieve the above-described objects, an optical printing apparatus, according to a seventh aspect of the present invention, is featured by such an optical printing apparatus for selectively exposing light with respect to a photosensitive recording medium to thereby form a gradation image thereon, comprising: image data input means for entering more than 3 colors of spectral image data; storage means for storing thereinto the entered spectral image data; an optical print head containing a plurality of light sources having different peak wavelengths within the same color system; and head driving means for converting the stored spectral image data into predetermined exposure time periods to drive the optical print head.
Also, an optical printing apparatus, according to eighth and ninth aspects of the present invention, is featured by that the optical print head contains a TN (twisted nematic) type light transmission control element for selectively exposing the light with respect to the photosensitive recording medium.
Also, an optical printing apparatus, according to a tenth aspect of the present invention, is featured by that the optical print head for outputting a plurality of light beams having different peak wavelengths within the same color system has different light intensity levels.